This invention relates to a coating agent for imparting electroconductivity to an insulator, more particularly to a coating agent for imparting electroconductivity, comprising carbon black dispersed in a hydrophilic solution of a maleic acid copolymer.
With development of electronic industries, it has been demanded to prevent static charges or shield electromagnetic waves against casing, housing box, package, etc. of electronic parts or electrical instruments, and it is becoming important to impart electroconductivity for this purpose.
In the prior art, for imparting electroconductivity to a housing box of electronic parts, it has been practiced to mold the box with, for example, a material having electroconductivity imparted thereto such as a thermoplastic resin kneaded with carbon black (Japanese Provisional Patent Publication No. 152736/1980). However, the material having electroconductivity imparted thereto becomes generally expensive, and yet also has problems in physical properties, and therefore, its use has been of itself limited. Also, it is known to apply an electroconductive coating material on a casing, etc. formed of an insulating material, but the electroconductive coating material has the problems such that it has not sufficient conductivity or that adhesion with the substrate is not sufficient, etc. Particularly, when the electroconductive coating material is applied onto paper, wood, etc. to impart electroconductivity thereto, although the surface resistance can be lowered, it was still insufficient in the point to lower the electrical resistance value between the front and the rear by penetration into the inner portion of such material.